题解 | #验证刷题效果，输出题目真实通过率#

select
  user_id,
  count(distinct if(result_info = 1, question_id, null)) / count(distinct question_id) as question_pass_rate,
  sum(result_info) / count(result_info) as pass_rate,
  count(question_id) / count(distinct question_id) as question_per_cnt
from
  done_questions_record
group by
  user_id
having
  question_pass_rate > 0.6;

分组的统计粒度是在组为单位的，总体体现为概括，窗口函数也是以小组为单位，但是窗口函数提现的是每行数据在小组内的相对位置。